As solar power has matured as a technology, companies have started applying it to more than just houses. Acting as an energy platform for our transport was an obvious application.
Solar: Will It Ever Power Our Vehicles
As an active technology, one of the first uses for solar power was on NASA spacecraft. Although not used for propelling the crafts, interested parties immediately started thinking about using solar power for getting us around in our daily lives. Alas, there were so many problems with the technology, including efficiency issues, that the idea never really gained much footing. With the massive popularity of hybrid vehicles, companies and research institutes are revisiting the idea.

Vehicles getting all of their energy from the sun are not a viable option at this time or for the near future. The problem is you simply can’t produce enough energy to meet the power needs. Until technology is developed to make the sunlight conversion process much more efficient, there really is not an answer to the problem. This technological advance, however, may not be far away.
Quantum dots are a form of nanotechnology that is being developed by numerous companies for solar power applications.

This technology essentially tries to create tiny solar robots to convert the sunlight to energy. Millions fit within small areas and the hope is the efficiency conversion rate will go through the roof. The companies are looking to create a platform where the robots would exist in paint. Yep, the paint on your home and car may eventually produce all the energy needed.
In the meantime, solar power applications are being developed with a focus on hybrids. The basic idea is to use solar power to provide energy to the batteries powering the hybrid cars. Put another way, it is a step towards the ultimate goal. Honda does not discuss its research, but is believed to have built a facility solely for this purpose and is dumping money into it hand over foot.
The creation of viable solar vehicles is dependent on the advances of the underlying technology. Solar hybrids should be on the market relatively quickly.

The big breakthrough, however, will be when viable commercial applications are developed using nanotechnology.